RESEARCH ARTICLE

Is patient empowerment the key to promote

adherence? A systematic review of the

relationship between self-efficacy, health

locus of control and medication adherence

Lilla Nafradi*☯, Kent Nakamoto☯, Peter J. Schulz☯

Institute of Communication and Health, Università della Svizzera italiana, Lugano, Switzerland

☯ These authors contributed equally to this work.

* lilla.nafradi@usi.ch

Abstract

Background

Current health policies emphasize the need for an equitable doctor-patient relationship, and

this requires a certain level of patient empowerment. However, a systematic review of the

empirical evidence on how empowerment affects medication adherence—the extent to

which patients follow the physician’s prescription of medication intake—is still missing. The

goal of this systematic review is to sum up current state-of-the-art knowledge concerning

the relationship between patient empowerment and medication adherence across medical

conditions. As our conceptualization defines health locus of control and self-efficacy as

being crucial components of empowerment, we explored the relationship between these

two constructs and medication adherence.

Methods

Relevant studies were retrieved through a comprehensive search of Medline and Psy-

chINFO databases (1967 to 2017). In total, 4903 publications were identified. After applying

inclusion and exclusion criteria and quality assessment, 154 articles were deemed relevant.

Peer-reviewed articles, written in English, addressing the relationship between empower-

ment (predictor) and medication adherence (outcome) were included.

Findings

High levels of self-efficacy and Internal Health Locus of Control are consistently found to

promote medication adherence. External control dimensions were found to have mainly

negative (Chance and God attributed control beliefs) or ambiguous (Powerful others attrib-

uted control beliefs) links to adherence, except for Doctor Health Locus of Control which had

a positive association with medication adherence. To fully capture how health locus of con-

trol dimensions influence medication adherence, the interaction between the sub-dimen-

sions and the attitudinal symmetry between the doctor and patient, regarding the patient’s

control over the disease management, can provide promising new alternatives.

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 1 / 23

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OPENACCESS

Citation: Nafradi L, Nakamoto K, Schulz PJ (2017)

Is patient empowerment the key to promote

adherence? A systematic review of the relationship

between self-efficacy, health locus of control and

medication adherence. PLoS ONE 12(10):

e0186458. https://doi.org/10.1371/journal.

pone.0186458

Editor: Monika R. Asnani, University of the West

Indies Faculty of Medical Sciences Mona, JAMAICA

Received: September 28, 2016

Accepted: October 2, 2017

Published: October 17, 2017

Copyright: © 2017 Nafradi et al. This is an open

access article distributed under the terms of the

Creative Commons Attribution License, which

permits unrestricted use, distribution, and

reproduction in any medium, provided the original

author and source are credited.

Data Availability Statement: All relevant data are

within the paper and its Supporting Information

files.

Funding: This work was supported by the Swiss

National Science Foundation (FNS 146 980), http://

www.snf.ch/en/Pages/default.aspx. The funders

had no role in study design, data collection and

analysis, decision to publish, or preparation of the

manuscript.

Discussion

The beneficial effect of patients’ high internal and concurrent physician-attributed control

beliefs suggests that a so-called “joint empowerment” approach can be suitable in order to

foster medication adherence, enabling us to address the question of control as a versatile

component in the doctor-patient relationship.

Introduction

Medication non-adherence—defined as the extent to which patients take medication in ways

other than those prescribed by their health care providers—is a serious obstacle to chronic

disease care, with a 50% average prevalence across conditions [1,2]. Non-adherence has

numerous patient, physician, medication and health care system related factors [1,2]. Several

characteristics of the patients, such as health literacy and medication beliefs influence adher-

ence [1–4]. Empowerment [5]—as an activating force that motivates some people to take their

health behavior and management of illnesses into their own hands—is also one of the patient-

related factors. Empowerment can be conceived as a personal disposition, referring to the

patient’s control and power in the medical context [6] or as a relational concept, emphasizing

the existing equity in the physician-patient relationship [7]. A collaborative doctor-patient

relationship can improve patient empowerment, i.e. the lack of concordance between doctors

and patients can lead to paternalism, and negotiated care can bring power balance into the

medical relationship [8]. As a matter of fact, the physicians by facilitating patient engagement

in the communication process can foster patient empowerment and better patient outcomes

[9].

Patient empowerment has been associated with positive health and clinical outcomes since

the concept made its mark in health care literature [5,10,11]. The outcomes considered [12]

include improved disease management [13–17], effective use of health services [13–15,18],

improved health status [19–21], and medication adherence [22,23]. The association between

empowerment and positive health behavior and clinical outcomes generally rests on the

assumption that patient autonomous activity is beneficial for their health condition. However,

in the case of medication adherence, this assumption might not always hold true. Highly

empowered patients might believe that they can make treatment decisions more or less by

themselves overruling the physician’s prescription. Indeed, intelligent non-adherence is

becoming a common term in the adherence literature, referring to patients´ intentional non-

adherence based on rational reasons, such as misdiagnosis or side-effects [24]. This definition

presupposes that non-adherence in case of these patients is the “right” choice which leads to

beneficial health outcomes, i.e. the patients are adequately health literate (having necessary

knowledge and decision-making skills about the medical treatment [25,26] to judge whether

adhere or not to the prescribed medication regimen. Similarly, Bader et al. (2006) defined criti-

cal adherence as the patients’ freedom to elect to interrupt or forgo a therapy, based on an

autonomous evaluation [27]. On the one hand, these forms of non-adherence are often viewed

as necessary, since adherence is favorable only if the medication is beneficial. On the other

hand, if such a high level of patient autonomy is not accompanied by an equally high level of

health literacy, the patient might be inclined to non-adherence in a presumptuous manner

putting his/her health into jeopardy [25]. Indeed, a recent review [28] investigating the conse-

quences of increasing patient empowerment reported that a high level of patient empower-

ment had a controversial relationship with adherence. Some aspects of patient empowerment

(such as information search and knowledge) promote adherence, while others (i.e. decision

A systematic review of the link between empowerment and adherence

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Competing interests: The authors have declared

that no competing interests exist.

participation) reduce therapy adherence [28]. These challenges call for all concerned to review

the empirical knowledge available on the relationship between empowerment and adherence.

A multidimensional conceptualization proposed originally in management literature

[29,30], and adapted to the health context by Schulz and Nakamoto [31], perceives empower-

ment as a motivational construct, holding that patients participate as autonomous actors in

health care decisions and consequentially take increased responsibility for such decisions

[31]). This concept has four components: 1. Meaningfulness (refers to the value of activities),

2. Competence (belief in one’s own capabilities), 3. Impact (belief in making a difference), and

4. Self-determination (refers to the extent to which a choice is characterized by autonomous

initiation). Based on this conceptualization, in the present review, patient empowerment is

operationalized as patients’ perceptions of their own capacity for disease management and

their beliefs about how much control they have over their own health outcomes. This defini-

tion leads to two main constructs constituting empowerment, which have been widely studied

in medication adherence literature: self-efficacy and health locus of control.

Self-efficacy is strongly related to the Competence dimension of the empowerment concept.

Self-efficacy draws on social-cognitive theory and can be defined as the individual’s belief in

his/her own ability to implement a specific behavior or a set of behaviors [32]. It can refer to

general [33] or context-specific perceptions of one´s own capacity to mobilize resources and

motivation to deal with certain situations and challenges [33]. General self-efficacy refers to a

stable sense of personal competence across situations [34,35]. It has been shown that a high

sense of efficacy can be associated with better health outcomes, greater achievement and better

social integration [32,36]. Moreover, self-efficacy was found to be the cornerstone of medica-

tion adherence in chronic mental illness [37] and the most prominent factor of adherence

across conditions within the socio-cognitive and self-regulation theories [38].

Health locus of control (HLOC) considers whether an individual’s source of reinforcement

for health-related behavior is internal or external. The former relates to a high, the latter to a

low level of Impact and Self-determination. The operationalization of the construct has since

gone through significant changes. A first approach by Rotter (1966) considered Internal

(ILOC) and External locus of control (ELOC) as two endpoints of a one-dimensional contin-

uum [39]. ILOC means that the individual’s sense of control over their health is directly related

to their own actions, while ELOC refers to the perception that one’s health is determined by

external factors. A later conceptualization, the Multidimensional Health Locus of Control

(MHLOC), kept internality (Internal HLOC), but divided external locus of control (External

HLOC) into specified sub-dimensions: Powerful Others, Doctor, Chance and God HLOC

[40,41]. HLOC has been widely used as a predictor of health behavior. Generally, it is assumed

that people with high Internal HLOC are more likely to behave in healthier ways than those

who do not believe that they have control over their health. However, an extremely high level

of Internal HLOC has been proposed to be problematic [42]. By contrast, someone with high

scores on the Chance HLOC subscale, believing that it is fate or chance that determines his/her

health status, is probably less likely to implement recommended health behavior. Powerful

Others HLOC is generally not assumed to encourage health behavior, except if others are sup-

portive of engaging in healthy behavior [43–45]. Wallston (2005) suggested incorporating

other variables such as self-efficacy as potential moderators when investigating how HLOC

influences health behavior [45]. This suggestion goes hand in hand with our empowerment

concept as it incorporates self-efficacy and health locus of control.

The role of patient empowerment in influencing medication adherence is a cardinal ques-

tion with major practical implications across all clinical and policy levels. Therefore, the

present systematic review seeks to answer the question, whether high level of patient empower-

ment is associated with greater medication adherence. Thus, the goal is to assess the relevant

A systematic review of the link between empowerment and adherence

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empirical findings about the relationship between patient empowerment and medication

adherence across medical conditions. Medication non-adherence was defined as the extent to

which the patients do not agree with/follow the physician’s recommendations regarding taking

the prescribed medication, measured by self-report, objective measures or mixed indicators.

As empowerment is regarded as consisting of HLOC and self-efficacy, we will address their

influence on medication adherence in two separate steps.

Materials and methods

Inclusion and exclusion criteria

The studies had to meet the following criteria in order to be included in the present systematic

review: (1) peer-reviewed articles, (2) written in English, (3) studies having observational or

experimental design, (4) addressing the relationship between medication adherence and at

least one aspect of empowerment, (5) empowerment should be considered either as an inde-

pendent variable or as a mediator, (6) medication adherence had to be assessed as an outcome

variable and (7) studies including an adult sample. We excluded papers which were not avail-

able in English, included a sample of youth, or focused on over the counter medications. More-

over, qualitative studies, commentaries, essays, study protocols, literature reviews, conceptual

papers and conference abstracts were also excluded.

Search strategy

In order to select a proper search strategy, a set of keywords was identified based on a prior

scoping search identifying the relevant academic jargon. Therefore, we initially searched sev-

eral databases including PROSPERO, COCHRANE library, Medline and PsychInfo for review

articles related to medication adherence and/or empowerment. Subsequently, a Thesaurus and

a PubMesh search was conducted in order to complete the list. In the main search, key terms

referring to empowerment and its related constructs were combined with either words related

to medication adherence or misuse. In order to include as many variants of the key terms as

possible, a wildcard search was used where this was deemed necessary. Keywords were con-

nected via the following Boolean operators: ‘Empowerment’ AND ‘Medication’ AND (‘Adher-

ence’ OR ‘Misuse’) (see: Table 1).

In order to identify relevant articles, two online databases were searched, one with a medi-

cal orientation (Medline) and the other with a focus on social sciences (PsychInfo). The search

included the literature published since 1966 to May 2017 in Medline and the publications in

the time period between 1967 to May 2017 in PsychInfo.

Data analysis and synthesis

The review was prepared in accordance with the PRISMA statement [46] (S1 Table). The origi-

nal search was carried out by one of the authors (L.N.), and yielded 4903 hits, which were then

screened on the basis of the titles and abstracts using three coders for their relevance, applying

the above-mentioned inclusion criteria. The interrater agreement was adequate (Cohen’s

kappa = 0.95) regarding which publications were deemed relevant and included for full text

Table 1. The Boolean search strategy applied in the present systematic review.

Empowerment Medication Adherence Misuse

empower* OR self-efficacy OR self-determin* OR

locus of control OR perceived autonomy OR

perception of autonomy OR overconfidence

medic* OR drug

OR prescrip*adherence OR non-adherence OR compliance OR non-

compliance OR concordance OR non-concordance OR

autonomous regulation of medication taking

self-medication OR

misuse OR abuse

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A systematic review of the link between empowerment and adherence

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assessment. A 13-item checklist developed by Wallace et al. (2006) was applied to assess the

quality of the included studies. The checklist contains specific questions in order to assess

whether the authors provide a clearly defined research question and appropriately describe the

theoretical background. Further questions probe the rigor of study design, data collection, data

analysis and the solidness of the derived conclusions [47]. The scores ranged from 0 to 13. The

interrater agreement regarding the quality of the papers was 79%. The interrater agreement

was calculated based on 10% of the hits, which is the recommended ratio of articles to be

coded by independent coders according to rule of thumb [48]. Relevant data, such as informa-

tion regarding the sample, methodology, the included measurement tools and outcomes were

extracted based on a previously developed coding scheme. In the case of the data extraction,

the interrater agreement was 85.6%. The coders of the abstract screening, data extraction and

quality assessment included one of the authors (L.N.) and research assistants with a health

communication background. Meta-analysis was not considered to be appropriate as the

included studies demonstrated large heterogeneity in terms of the conceptualization and oper-

ationalization of empowerment as well as medication adherence [49].

Results

154 articles were deemed to be fit for inclusion based on the full text analysis. None of the stud-

ies were judged to have a quality so poor that they had to be excluded. The average quality

score was 11.93 out of 13 (SD = 1.6). If the articles reported more than one outcome about the

relationship between the empowerment-related constructs and adherence, each result was

included separately in the review. Fig 1 provides an overview of the selection process.

Overview of the results

The vast majority of the studies were conducted in North America (n = 107). Other studies

took place in Europe (n = 25), Asia (n = 11), Eurasia (n = 1), Australia) (n = 5), South America

(n = 4) and Africa (n = 1).

The studies involved patients diagnosed with various disease groups: HIV/AIDS (n = 52),

heart and vascular disorders (n = 18), respiratory diseases (n = 15), renal (n = 12) and of the

endocrine system (n = 11). Some studies involved participants suffering from diseases of the

brain and nervous system (n = 8), musculoskeletal (n = 6) and digestive system (n = 4), cancer

(n = 4) and other conditions (n = 17). A small number of studies concerned patients diagnosed

with psychological conditions (n = 7). S2 Table provides an overview of the sample

characteristics.

We identified numerous scales measuring a given dimension of empowerment based on

our operational definition. As far as locus of control is concerned, most of the studies applied

either a one dimensional (RIELCS) [39] or a multidimensional measurement (MHLOC Scale)

[40] of the concept. Our search revealed studies using several types of self-efficacy beliefs: med-

ication adherence, disease-management, general, coping self-efficacy, etc. Only a minority of

the included articles focused on other empowerment-related constructs, such as competence

or self-regulation.

Concerning the operationalization of medication adherence, we can distinguish three

types: objective measures (using pill count, patients’ medical outcomes or pharmacy records

as a proxy of adherence), subjective measures i.e. where patients provided self-reported ques-

tionnaires or structured interviews, and lastly mixed measures which apply subjective and

objective adherence measures simultaneously. As there is no agreement on a single method

which performs well across all criteria [50], we decided to include all of the studies regardless

A systematic review of the link between empowerment and adherence

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Records iden fied through database searching

(n =4903)

Scre

enin

g In

clud

ed

Elig

ibili

ty

Iden

fica

on

Records a er duplicates removed (n =4493)

Records screened (n =4493)

Records excluded (n =4225)

Full-text ar cles assessed for eligibility

(n = 268)

Full-text ar cles excluded, with reasons

(n =114) Qualita ve (11)

Abstract (2) Commentary/essay (3) Children sample (10)

Not available in English (9) Not relevant

concept/rela onship (61) Study protocol (4)

Review (4) Over-the-counter

medica on (2) Unrelated interven on

study (4) Conceptual paper (4)

Studies included in synthesis (n =154)

Fig 1. Flow diagram of the study selection process, adapted from Moher et al. (2009).

https://doi.org/10.1371/journal.pone.0186458.g001

A systematic review of the link between empowerment and adherence

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of the adherence measure applied. See S3 Table for an overview of the included studies and S4

Table for their quality assessment score.

The relationship between self-efficacy and medication adherence

The identified studies addressing the relationship between adherence and self-efficacy focused

mainly on medication adherence, disease-management and general self-efficacy (See: Table 2).

Medication adherence self-efficacy refers to a belief in the patient’s capacity to follow a

prescribed medical regimen in challenging situations [51]. Most of the articles (59 out of 66

studies) found a positive link between medication adherence self-efficacy and adherence [52–

100], and among these 9 studies also reported that self-efficacy had a mediator role [101–110].

Only three studies considered adherence-self-efficacy solely as a mediator [111–113] and four

reported no relationship [114–117].

Disease management self-efficacy refers to the patients’ beliefs in their capacity to manage

disease in general [118,119) or condition-specific self-management behavior [120,121]. The

studies investigating the relationship between disease management self-efficacy and medication

adherence applied specific scales developed to measure efficacy beliefs about implementing

tasks related to managing a given condition. The majority of the studies (16 out of 20) reported

a positive association [118,122–136], while only 3 reported no relationship [119,137,138] and 1

suggested mixed results [139].

General self-efficacy refers to one’s perceived competence across a wide array of life

domains (36). General self-efficacy had, in most of the cases (4 studies out of 6), a positive asso-

ciation with adherence [140–143], while 2 studies did not find any relationship [144,145]. Some

studies simultaneously applied general as well as disease or drug specific self-efficacy measures

and investigated which one was more likely to predict self-reported adherence to medication.

Two of the studies reported that disease specific self-efficacy was a more important predictor of

adherence than generic self-efficacy [142,146]; the third study reported no relationship [145].

Studies focusing on other domain-specific self-efficacy measures reported a positive link

between adherence and self-efficacy in patient-physician interactions [147,148], coping self-

efficacy [149], bi-cultural self-efficacy [150], self-efficacy for managing negative mood, adher-

ing to medication, symptoms and fatigue management, communicating with health care pro-

viders and getting support from others [151]. Self-efficacy when disclosing drug use to

providers and for safer drug use were not as effective predictors of self-reported adherence as

adherence self-efficacy [52]. Self-efficacy scores for physical function were seen to have a nega-

tive link to adherence[145].

Concerning the different adherence measures, a positive association between self-efficacy

and adherence was reported in a greater proportion in studies using subjective (87%) or mixed

measures (79%), compared to studies applying objective adherence measures (66.6%).

The relationship between HLOC and medication adherence

HLOC was predominantly measured using two instruments: the one-dimensional RIELCS

measure [39] and the MHLOC [41,152,153], which is a multidimensional instrument.

Table 2. The relationship found between different types of self-efficacy and medication adherence (N = 92).

Relationship with medication adherence Positive relationship Negative relationship No relationship Mediator Mixed results All

Types of self-

efficacy

Medication

adherence

89% (n = 59) - 6% (n = 4) 5%

(n = 3)

- 100%

(n = 66)

Disease

management

80% (n = 16) - 15% (n = 3) - 5% (n = 1) 100%

(n = 20)

General 66,6% (n = 4) - 33,3% (n = 2) - 100% (n = 6)

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First, we considered the relationship between the RIELCS and medication adherence. Of

the 9 studies, in four cases (45%) ILOC was found to be more beneficial for medication adher-

ence than ELOC [154–157]. By contrast, two studies (22%) found that ELOC was related to

better medication adherence than ILOC [158,159]. Finally, in three (33%) studies, ILOC and

ELOC orientation did not distinguish between compliant and non-compliant patients [160–

162].

The results which relate to MHLOC dramatically differ in terms of its sub-dimensions:

Internal HLOC and External HLOC. Many studies (10 out of 26 studies) reported a positive

association between Internal HLOC and adherence [81,101,163–170]; only a single study

found a negative relationship [171]. Another study reported that a high level of Internal HLOC

promotes critical adherence or non-adherence, i.e. how patients decided to follow or forgo a

therapy based on autonomous evaluation [27]. There was a high number of null findings, i.e.

15 studies reported no relationship between IHLOC and adherence [160,172–185].

Examining the MHLOC External sub-dimensions respectively (i.e. Chance, God, Powerful

others and Doctor HLOC) allowed us to explore and compare their variable associations with

adherence. A large enough proportion of the studies (5 out of 18) found a negative link between

Chance HLOC and adherence [170,183,186–188], while only one study reported a positive rela-

tionship (189). Twelve studies reported null findings [172,174–177,179,180,182,183,185,190,191].

God HLOC had a negative association with medication adherence [172]. In the case of the Pow-

erful others HLOC, the findings are ambiguous, as the number of studies reporting a negative

relationship with adherence [169,181,183,192,193] is only slightly higher (5 studies) than the stud-

ies which found a positive link (4 studies) [171,189,194,195]. In addition, 11 studies reported no

relationship [172,174–177,180,182–184,191,196]. Doctor HLOC, by contrast, seems to promote

adherence, as studies unequivocally found that people characterized with high Doctor HLOC

tend to comply better with their given medical regimen (3 studies) [169,172,194]. However, in

this case 3 studies also found no association with adherence [174,183,197] (see: Table 3).

The studies applying subjective adherence measures reported more association either in a

positive or negative direction (58.5%) between the HLOC dimensions and adherence com-

pared to the studies applying mixed (14.3%) or objective (40%) adherence measures.

HLOC can also be conceived as a mediator of the relationship between adherence and vari-

ous other predictors, such as perceived necessity of the treatment [198], social support [199],

self-efficacy and outcome expectancy [200], competence [175,201] and hostility [202]. Alterna-

tively, MHLOC can also explain to what degree any identified medication non-adherence is

deliberate [203].

Health condition-specific patterns

Regarding the role of self-efficacy in predicting adherence across health conditions, in patients

diagnosed with digestive system or musculoskeletal diseases, multiple sclerosis, epilepsy, head-

ache and psychiatric conditions, all studies reported a positive association between adherence

and self-efficacy. In HIV, respiratory diseases, cancer, heart and vascular disorders, diabetes

Table 3. The relationship between MHLOC and adherence (N = 71).

MHLOC dimension Positive relationship Negative relationship No relationship All

Internal HLOC 38% (n = 10) 4% (n = 1) 58% (n = 15) 100% (N = 26)

External HLOC Powerful others 20% (n = 4) 25% (n = 5) 55% (n = 11) 100% (n = 20)

Doctor 50% (n = 3) - 50% (n = 3) 100% (n = 6)

God - 100% (n = 1) - 100% (n = 1)

Chance 5% (n = 1) 28% (n = 5) 67% (n = 12) 100% (n = 18)

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and renal diseases, the majority of the studies reported a positive association between adher-

ence and self-efficacy, but there were some null findings, too.

Concerning how HLOC affects medication adherence, the studies involving patients diag-

nosed with HIV, cancer, diabetes and digestive system diseases reported that Internal HLOC

fosters, while External HLOC dimensions appear to hinder adherence. In other conditions, the

relationship between adherence and HLOC was more ambigous, i.e. in heart and vascular dis-

orders and mental conditions. Besides Internal HLOC, high levels of Doctor HLOC emerged

as a significant predictor of greater adherence in two conditions: respiratory diseases [172,194]

and renal disease [169,201].

Other important predictors of adherence were the patients’ autonomy preference regarding

respiratory diseases [204], perceived autonomy among renal transplant patients [205], self-reg-

ulation in heart failure patients [206] and perceived competence [207], autonomous motiva-

tion [180,207] and treatment-related empowerment [208] in HIV. In patients diagnosed with

diabetes, perceived competence [209], diabetes empowerment [22] and Diabetes HLOC [210]

were predictors of adherence.

Discussion

In the present study, the relationship between patient empowerment and medication adher-

ence was reviewed, with special focus on the two constructs deemed to be the central facets of

empowerment: HLOC and self-efficacy.

An overview of the relationship between self-efficacy and adherence

Our results confirm that self-efficacy is a strong predictor of medication adherence. Positive

association with adherence holds for of all types of self-efficacy: general, medication adherence,

disease management and other domain specific measures. Our findings confirm and expand

the findings of McCann et al.’s review [37], which highlighted the importance of self-efficacy

in medication adherence in chronic mental illness, as we found that self-efficacy was an impor-

tant predictor of adherence both in the case of mental and somatic diseases. On the one hand,

the effect of self-efficacy in fostering adherence is so robust that it holds regardless of the type

of self-efficacy applied and across all medical conditions. On the other hand, specific measures

of both medication adherence self-efficacy and disease management self-efficacy show a posi-

tive association with adherence compared to general self-efficacy more consistently. Thus,

future research might apply context-specific measures for predicting medication adherence,

considering that the most consistent adherence self-efficacy seems to be associated with adher-

ence. However, this strong link might arise from the operational overlap between these con-

structs, as medication adherence questionnaires sometimes measure barriers to medication

adherence, such as certain aspects of adherence self-efficacy [50].

The relationship between HLOC and adherence

The findings show that Internal HLOC predominantly has a positive link with medication

adherence, while External HLOC dimensions have variable associations.

Studies applying the one-dimensional RIELCS [39] showed a trend suggesting that ILOC is

more favorable for adherence than ELOC, but the difference was small. The characteristics of

this measure might account for the contradicting findings, as the RIELCS does not distinguish

the dimensions of ELOC, and this might lead to individual differences in the interpretation.

Alternatively, treating ILOC and ELOC as opposite ends of one continuum may not capture

its effect on adherence. Therefore, the MHLOC Scale [40] seems to be a more appropriate tool

when examining the relationship between HLOC and adherence.

A systematic review of the link between empowerment and adherence

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As far as MHLOC is concerned, a clear majority of the studies reported a positive relationship

between Internal HLOC and adherence, which confirms that patients’ beliefs of being in control

of their own health (a facet of high empowerment) is associated with greater adherence. How-

ever, the relationship between External HLOC and adherence is variable, as the sub-facets of

HLOC show variable relationships with adherence. In accordance with our assumptions, Chance

HLOC, which can signal low empowerment, showed a negative association with medication

adherence. God HLOC also had a negative link to adherence, but only one study looked into

this relationship [172]. The number of studies reporting a positive and a negative association

between Powerful others HLOC and adherence were almost equal. The effect of Powerful others

HLOC on adherence might depend on whether these others support or discourage the patients

to adhere [43–45]. Indeed, Doctor HLOC seems to be the most beneficial element of External

HLOC promoting adherence, especially when it was concurrent with high Internal HLOC [169].

The variable associations of different External HLOC dimensions with medication adherence

indicate that the perceived control dimension of empowerment is far from homogenous. In par-

ticular, Doctor HLOC fosters adherence, highlighting how, in a medication management con-

text, not only the belief in one’s own ability and control are beneficial, but also acknowledging

the medical expertise and the doctor’s influence on one’s health can be auspicious.

Therefore, to fully understand the relationship between HLOC beliefs and adherence,

examining solely the main effects of the sub-dimensions may not be sufficient, but looking

into the interaction effects between Internal HLOC and External HLOC as well as External

HLOC subdimensions on medical regimen adherence might be more fruitful [167,211]. Some

studies recognized the importance of the interactional component of patient empowerment,

therefore they addressed how the attitudinal symmetry in the doctor-patient dyads regarding

patients’ control over health outcomes influenced medication adherence [212,213]. Indeed,

patients who held highly similar beliefs to their physicians regarding a patients’ degree of con-

trol over their own health, adhered more to their medication regimen than patients who

believed more strongly in their own personal control over their health than their doctor did

[213].

More than half of the studies report no link between HLOC and medication adherence.

Wallston suggested that HLOC does not operate alone to determine a behavior [44], and that

other factors such as self-efficacy should be incorporated as a moderator [45]. This idea is com-

patible with the empowerment concept, which emphasizes that these constructs can jointly

explain health behavior such as adherence. The findings seem robust and applicable across dif-

ferent cultures and countries. However, the North American sample may be considered overly

representative in this review (close to 70%); therefore, an international or cultural comparison

may not be well-grounded or representative here. Moreover, the majority of the sample being

North American may have impacted findings, since the health care system in the United States

is characterized by an advanced state of technology, private markets and pluralism [214].

Patients in the US are expected to decide about purchasing a health insurance plan choosing

from various for-profit commercial insurance companies or from non-profit insurers [214]

based on several factors (e.g. premium, deductible and out-of-pocket costs), which might fos-

ter patient empowerment compared to countries with a single nationwide system of health

insurance.

‘Joint empowerment’ as a facilitator of adherence: Theoretical,

operational and policy implications

The review suggests that a shift might be necessary in the conceptual as well as the operational

ways of considering patient empowerment. The current literature offers two seemingly

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 10 / 23

opposite approaches: conceiving empowerment as a relational [7] versus an intrapersonal con-

cept [6]. Our findings suggest that in the medication adherence context the individual and

relational aspects of empowerment should be viewed as the two sides of the same coin. We

argue that patients need a high level of self-efficacy and internal health control beliefs, but they

also have to be capable of sharing the control over their disease management with the physi-

cian. If we conceptualize empowerment in the above described manner, that would require

further research to capture the relational empowerment as a dynamic feature of the doctor-

patient relationship unfolding during the medical encounter. On the individual level, that

would also require a shift from understanding empowerment as patient autonomy to a frame-

work which would consider it as the patients’ perceived capability to cooperate effectively with

the physician and sharing control with him/her. More research would be necessary to discover

the right amount of control assigned to the patient and to the physician in the different con-

texts, i.e. in different conditions or stages of the illness, etc.

The theoretical shift suggested above would call for an operational revolution of empower-

ment, i.e. developing new measures about the patients’ beliefs about being able to collaborate

and discuss issues with the physician, and asking for advice when necessary. As this definition

of empowerment unavoidably presupposes the need of the patients’ ability to judge when they

can act autonomously and when they would be better off asking for guidance from the physi-

cian, it raises the question of whether such a high level of empowerment is beneficial without

the necessary health literacy skills [215].

To sum up, patient empowerment can promote medication adherence, but it requires a co-

constructed sense of control in the doctor-patient dyad. This has implications for the clinical

practice and policy making, i.e.instead of forcing or reinforcing the vision of an overly empow-

ered patient (which can be burdensome for some patients [216,217] and demanding for many

health care providers), an equilibrium should be established, in which both parties are inter-

changeably in control. This requires the health care providers facilitating patient empower-

ment (internal HLOC and self-efficacy), but also pointing out the importance of relying on the

medical expertise of the physicians (Doctor HLOC) while choosing together the best possible

treatment. As finding this equilibrium might be challenging, it requires building a strong col-

laborative doctor-patient relationship and continuous negotiation during the medical encoun-

ter. Moreover, patients’ level of health literacy should be taken into account and facilitated, as

a recent paper showed that empowerment has a stronger link to better health status among the

adequately health literate patients [218]. Most importantly, this approach has the capacity to

reconcile the notion of an empowered patient and the shared decision making framework

[219], without raising the dilemma of power or imbalanced control in the doctor-patient

relationship.

Limitations

This systematic review is not without limitations. First, our approach might not have captured

other conceptualizations of empowerment existing in relevant literature. Second, no quantita-

tive value can be presented to demonstrate the relationship between empowerment and medi-

cation adherence, as neither of the concepts is currently operationalized consistently across

studies, which would allow us to conduct a meta-analysis. Thirdly, the medication adherence

measures only rarely distinguish between the intentional and unintentional dimensions of

non-adherence, possibly leading to a cancelling out of the relationship between empowerment

and intentional non-adherence, with the inclusion of unintentional non-adherence. Studies

using objective measures more often reported null findings compared to studies applying sub-

jective adherence measures, introducing potential measurement bias to the analysis. Fourthly,

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 11 / 23

the vast majority of the included studies had a cross-sectional correlational design, therefore

we cannot draw any causal inference regarding the relationship between empowerment and

adherence from them. Moreover, we included observational and interventional studies

together in the systematic review, which introduces substantial heterogeneity. However, given

the importance of findings emerging from interventional studies for the practical implications

and insights gained in causal relationships, including intervention studies might merit particu-

lar prominence. Furthermore, we may unavoidably have missed unpublished studies or those

that were not captured by the search strategy, potentially leading to publication bias. However,

we put a great effort into avoiding publication bias with such preventative measures as search-

ing without limiting by outcome [220]. The study samples were heterogeneous regarding char-

acteristics such as medical condition, age and education, which may have affected the results.

The applied quality assessment checklist did not recommend a cut-off score for low quality,

thus all studies with different quality scores were included in the final analysis. Lastly, we

included only papers published in the English language, and this might have resulted in miss-

ing some relevant work written in other languages.

Conclusions

Our findings indicate that a balanced view would be the most beneficial for facilitating adher-

ence, one alongside which the patients’ beliefs in their own capacity and control over their

health is simultaneously present with their acknowledgment of the physician’s role in their dis-

ease management. The integration of the relational and individual nature of the construct to a

so-called ‘joint empowerment’ approach enables us to address the question of control as a ver-

satile component in a doctor-patient dyad.

Supporting information

S1 Table. PRISMA checklist.

(DOCX)

S2 Table. Sample characteristics.

(DOC)

S3 Table. Overview of the included studies.

(DOCX)

S4 Table. Quality assessment.

(XLSX)

Acknowledgments

The authors wish to thank colleagues and research assistants for their help with the data extrac-

tion and quality assessment of the various papers.

Author Contributions

Conceptualization: Lilla Nafradi, Kent Nakamoto, Peter J. Schulz.

Data curation: Lilla Nafradi.

Formal analysis: Lilla Nafradi.

Funding acquisition: Kent Nakamoto, Peter J. Schulz.

Methodology: Lilla Nafradi.

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 12 / 23

Project administration: Lilla Nafradi, Kent Nakamoto, Peter J. Schulz.

Supervision: Kent Nakamoto, Peter J. Schulz.

Writing – original draft: Lilla Nafradi.

Writing – review & editing: Kent Nakamoto, Peter J. Schulz.

References1. Brown MT, Bussell JK. Medication adherence: WHO cares? Mayo Clin Proc. 2011; 86:304–14. https://

doi.org/10.4065/mcp.2010.0575 PMID: 21389250

2. De Geest S, Sabate E. Adherence to long-term therapies: Evidence for action. Eur J Cardiovasc Nurs.

2003; 2:323. https://doi.org/10.1016/S1474-5151(03)00091-4 PMID: 14667488

3. McHorney CA, Zhang NJ, Stump T, Zhao X. Structural equation modeling of the proximal-distal contin-

uum of adherence drivers. Patient Prefer Adherence. 2012; 6:789–804. https://doi.org/10.2147/PPA.

S36535 PMID: 23204839

4. Tibaldi G, Clatworthy J, Torchio E, Argentero P, Munizza C, Horne R. The utility of the Necessity—

Concerns Framework in explaining treatment non-adherence in four chronic illness groups in Italy.

Chronic Illn. 2009; 5:129–33. https://doi.org/10.1177/1742395309102888 PMID: 19474235

5. Rappaport J. Terms of empowerment/exemplars of prevention: Toward a theory for community psy-

chology. Am J Community Psychol. 1987; 15(2):121–48. PMID: 3604997

6. Rissel C. Empowerment: the holy grail of health promotion? Health Promot Int. 1994; 9(1):39–47.

7. Sherwin S. No longer patient: Feminist ethics and health care. Philadelphia: Temple Univ Press;

1992.

8. Goodyear-Smith F, Buetow S. Power issues in the doctor-patient relationship. Heal Care Anal. 2001; 9

(4):449–62.

9. Roter D. Empowering patient communication. In: Kahan S, Gielen AC et al., editors. Baltimore, MD,

US: Johns Hopkins University Press; 2014. p. 473–84.

10. Rappaport J. In praise of paradox: A social policy of empowerment over prevention. Am J Community

Psychol. 1981; 9(1):1–25. PMID: 7223726

11. Zimmerman MA, Rappaport J. Citizen participation, perceived control, and psychological empower-

ment. Am J Community Psychol. 1988; 16(5):725–50. PMID: 3218639

12. World Health Organization. (Wallerstein N) What is the Evidence on Effectiveness of Empowerment to

Improve Health? 2006, p37.

13. Lorig KR, Sobel DS, Ritter PL, Laurent D, Hobbs M. Effect of a self-management program on patients

with chronic disease. Eff Clin Pract. 2001; 4(6):256–62. PMID: 11769298

14. Lorig KR, Ritter PL, Gonzalez VM. Hispanic chronic disease self-management: a randomized commu-

nity-based outcome trial. Nurs Res. 2003; 52(6):361–9. PMID: 14639082

15. Lorig KR, Ritter P, Stewart AL, Sobel DS, BW B Jr, Bandura A, et al. Chronic disease self-manage-

ment program: 2-year health status and health care utilization outcomes. Med Care. 2001; 39

(11):1217–23. PMID: 11606875

16. Endicott L, Corsello P, Prinzi M, Tinkelman DG, Schwartz A. Operating a sustainable disease man-

agement program for chronic obstructive pulmonary disease. Lippincotts Case Manag. 2003; 8

(6):252–4. PMID: 14646783

17. Roberts KJ. Patient empowerment in the United States: a critical commentary. Heal Expect. 1999; 2

(2):82–92.

18. Tsay S-L, Hung L-O. Empowerment of patients with end-stage renal disease—a randomized con-

trolled trial. Int J Nurs Stud. 2004; 41(1):59–65. PMID: 14670395

19. Bergsma LJ, Carney ME. Effectiveness of health-promoting media literacy education: a systematic

review. Health Educ Res. 2008; 23(3):522–42. https://doi.org/10.1093/her/cym084 PMID: 18203680

20. Bergsma LJ. Empowerment Education The Link between Media Literacy and Health Promotion. Am

Behav Sci. 2004; 48(2):152–64.

21. Wallerstein N. What is the evidence on effectiveness of empowerment to improve health? [Health Evi-

dence Network Report]. Copenhagen: World Health Organization Regional Office for Europe; 2006.

22. Hernandez-Tejada MA, Campbell JA, Walker RJ, Smalls BL, Davis KS, Egede LE. Diabetes Empow-

erment, Medication Adherence and Self-Care Behaviors in Adults with Type 2 Diabetes. Diabetes

Technol Ther. 2012; 14(7):120423110411000.

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 13 / 23

23. Webb DG, Horne R, Pinching AJ. Treatment-related empowerment: preliminary evaluation of a new

measure in patients with advanced HIV disease. Int J STD AIDS. 2001 Feb; 12(2):103–7. https://doi.

org/10.1258/0956462011916875 PMID: 11236098

24. Britten N. Patients’ ideas about medicines: a qualitative study in a general practice population. Br J

Gen Pract. 1994; 44(387):465–8. PMID: 7748635

25. Schulz PJ, Nakamoto K. Health literacy and patient empowerment in health communication: The

importance of separating conjoined twins. Patient Educ Couns. 2013; 90(1):4–11. https://doi.org/10.

1016/j.pec.2012.09.006 PMID: 23063359

26. Sørensen K, Van den Broucke S, Fullam J, Doyle G, Pelikan J, Slonska Z, et al. Health literacy and

public health: A systematic review and integration of definitions and models. BMC Public Health. 2012;

12(1):80.

27. Bader A, Kremer H, Erlich-Trungenberger I, Rojas R, Lohmann M, Deobald O, et al. An adherence

typology: coping, quality of life, and physical symptoms of people living with HIV/AIDS and their adher-

ence to antiretroviral treatment. Med Sci Monit. 2006; 12(12):CR493–500. PMID: 17136004

28. Prigge JK, Dietz B, Homburg C, Hoyer WD, Burton JL. Patient empowerment: A cross-disease explo-

ration of antecedents and consequences. Int J Res Mark. 2015; 32(4):375–86.

29. Thomas KW, Velthouse BA. Cognitive elements of empowerment: An “interpretive” model of intrinsic

task motivation. Acad Manag Rev. 1990; 15(4):666–81.

30. Spreitzer G. Psychological Empowerment in the Workplace: Dimensions, Measurement, and Valida-

tion. Academy of Management Journal. 1995. p. 1442–65.

31. Schulz PJ, Nakamoto K. “Bad” literacy, the Internet, and the limits of patient empowerment. 2011

AAAI Spring Symposium Series. 2011.

32. Bandura A. Self-efficacy: toward a unifying theory of behavioral change. Psychological Review. 1977.

191–215. PMID: 847061

33. Scholz U, Gutierrez Doña B, Sud S, Schwarzer R. Is General Self-Efficacy a Universal Construct? Eur

J Psychol Assess. 2002; 18(3):242–51.

34. Schwarzer R, Jerusalem M. Skalen zur Erfassung von Lehrer-und Schulermerkmalen. Dokumentation

der Psychom Verfahren im Rahmen der Wissenschaftlichen Begleit des Model Selbstwirksame Schu-

lenBerlin. 1999;

35. Sherer M, Maddux JE, Mercandante B, Prentice-Dunn S, Jacobs B, Rogers RW. The self-efficacy

scale: Construction and validation. Psychol Rep. 1982; 51(2):663–71.

36. Jerusalem M, Schwarzer R. Self-efficacy as a resource factor in stress appraisal processes. In

Schwarzer R. (Ed.), Self-efficacy: Thought control of action (pp. 195–213). Washington DC:

Hemisphere.

37. McCann TV, Clark E, Lu S. The self-efficacy model of medication adherence in chronic mental illness. J

Clin Nurs. 2008; 17(11c):329–40. https://doi.org/10.1111/j.1365-2702.2008.02354.x PMID: 26327416

38. Holmes EA, Hughes DA, Morrison VL. Predicting Adherence to Medications Using Health Psychology

Theories: A Systematic Review of 20 Years of Empirical Research. Value Heal. 2014; 17(8):863–76.

39. Rotter JB. Generalized expectancies for internal versus external control of reinforcement. Psychol

Monogr. 1966; 80(1):1. PMID: 5340840

40. Wallston KA, Wallston BS, DeVellis R. Development of the multidimensional health locus of control

(MHLC) scales. Heal Educ Behav. 1978; 6(1):160–70.

41. Wallston KA, Malcarne VL, Flores L, Hansdottir I, Smith CA, Stein MJ, et al. Does God determine your

health? The God locus of health control scale. Cognit Ther Res. 1999; 23(2):131–42.

42. Rotter JB, Hochreich DJ. Personality. Glenview, IL: Scott. Foresman, 1975.

43. Wallston KA, Wallston BS. Who is responsible for your health. In: eds. The construct of health locus of

control in social psychology of health and illness. City: Lawrence Erlbaum Hillsdale, NJ; 1982. 65–95.

44. Wallston KA. The importance of placing measures of health locus of control beliefs in a theoretical con-

text. Health Educ Res. 1991; 6(2):251–2.

45. Wallston. The Validity of the Multidimensional Health Locus of Control Scales. J Health Psychol. 2005;

10(5):623–31. https://doi.org/10.1177/1359105305055304 PMID: 16033784

46. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JP a, et al. The PRISMA state-

ment for reporting systematic reviews and meta-analyses of studies that evaluate health care interven-

tions: explanation and elaboration. J Clin Epidemiol. 2009; 62:e1–34. https://doi.org/10.1016/j.jclinepi.

2009.06.006 PMID: 19631507

47. Wallace A, Croucher K, Bevan M, Jackson K, O’Malley L, Quilgars D. Evidence for policy making:

some reflections on the application of systematic reviews to housing research. Hous Stud. 2006; 21

(2):297–314.

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 14 / 23

48. Neuendorf KA. The content analysis guidebook. London: Sage; 2002.

49. Lipsey MW, Wilson DB. Practical meta-analysis. Thousand Oaks, CA: Sage; 2001.

50. Nguyen T-M-U, Caze A La, Cottrell N. What are validated self-report adherence scales really measur-

ing?: a systematic review. Br J Clin Pharmacol. 2014; 77:427–45. https://doi.org/10.1111/bcp.12194

PMID: 23803249

51. Ogedegbe G, Mancuso CA, Allegrante JP, Charlson ME. Development and evaluation of a medication

adherence self-efficacy scale in hypertensive African-American patients. J Clin Epidemiol. 2003; 56

(6):520–9. PMID: 12873646

52. Arnsten JH, Li X, Mizuno Y, Knowlton AR, Gourevitch MN, Handley K, et al. Factors associated with

antiretroviral therapy adherence and medication errors among HIV-infected injection drug users. J

Acquir Immune Defic Syndr. 2007; 46 Suppl 2:S64–71.

53. Atkinson JS, Schonnesson LN, Williams ML, Timpson SC. Associations among correlates of schedule

adherence to antiretroviral therapy (ART): a path analysis of a sample of crack cocaine using sexually

active African-Americans with HIV infection. AIDS Care. 2008; 20:253–62. https://doi.org/10.1080/

09540120701506788 PMID: 18293137

54. Begley K, McLaws M-L, Ross MW, Gold J. Cognitive and behavioural correlates of non-adherence to

HIV anti-retroviral therapy: Theoretical and practical insight for clinical psychology and health psychol-

ogy. Clin Psychol. 2008; 12(1):9–17.

55. Breaux-Shropshire TL, Brown KC, Pryor ER, Maples EH. Relationship of blood pressure self-monitor-

ing, medication adherence, self-efficacy, stage of change, and blood pressure control among munici-

pal workers with hypertension. Workplace Health Saf. 2012; 60(7):303–11. https://doi.org/10.3928/

21650799-20120625-04 PMID: 22767462

56. Brown JL, Littlewood RA, Vanable PA. Social-cognitive correlates of antiretroviral therapy adherence

among HIV-infected individuals receiving infectious disease care in a medium-sized northeastern US city.

AIDS Care. 2013; 25(9):1149–58. https://doi.org/10.1080/09540121.2012.752566 PMID: 23311323

57. Brus H, Van De Laar M, Taal E, Rasker J, Wiegman O. Determinants of compliance with medication in

patients with rheumatoid arthritis: The importance of self-efficacy expectations. Patient Educ Couns.

1999; 36:57–64. PMID: 10036560

58. Burra TA, Chen E, McIntyre RS, Grace SL, Blackmore ER, Stewart DE. Predictors of self-reported

antidepressant adherence. Behav Med. 2007; 32:127–34. https://doi.org/10.3200/BMED.32.4.127-

134 PMID: 17348428

59. Catz SL, Kelly JA, Bogart LM, Benotsch EG, McAuliffe TL. Patterns, correlates, and barriers to medi-

cation adherence among persons prescribed new treatments for HIV disease. Health Psychol. 2000;

19(2):124–33. PMID: 10762096

60. Chao J, Nau DP, Aikens JE, Taylor SD. The mediating role of health beliefs in the relationship between

depressive symptoms and medication adherence in persons with diabetes. Res Soc Adm Pharm.

2005; 1:508–25.

61. Chesney MA, Ickovics JR, Chambers DB, Gifford AL, Neidig J, Zwickl B, et al. Self-reported adher-

ence to antiretroviral medications among participants in HIV clinical trials: the AACTG adherence

instruments. AIDS Care. 2000; 12(3):255–66. https://doi.org/10.1080/09540120050042891 PMID:

10928201

62. Colbert AM, Sereika SM, Erlen JA. Functional health literacy, medication-taking self-efficacy and

adherence to antiretroviral therapy. J Adv Nurs. 2013; 69:295–304. https://doi.org/10.1111/j.1365-

2648.2012.06007.x PMID: 22489684

63. Cook PF, Emiliozzi S, El-Hajj D, McCabe MM. Telephone nurse counseling for medication adherence

in ulcerative colitis: A preliminary study. Patient Educ Couns. 2010; 81(2):182–6. https://doi.org/10.

1016/j.pec.2009.12.010 PMID: 20079598

64. Cook PF, McCabe MM, Emiliozzi S, Pointer L. Telephone Nurse Counseling Improves HIV Medication

Adherence: An Effectiveness Study. J Assoc Nurses AIDS Care. 2009; 20(4):316–25. https://doi.org/

10.1016/j.jana.2009.02.008 PMID: 19576548

65. Criswell TJ, Weber CA, Xu Y, Carter BL. Effect of self-efficacy and social support on adherence to anti-

hypertensive drugs. Pharmacotherapy. 2010; 30(5):432–41. https://doi.org/10.1592/phco.30.5.432

PMID: 20411995

66. Denhaerynck K, Abraham I, Gourley G, Drent G, Vleeschouwer P De, Papajcik D, et al. Validity testing

of the long-term medication behavior self-efficacy scale. J Nurs Meas. 2003; 11(3):267–82. PMID:

15633781

67. Elder K, Ramamonjiarivelo Z, Wiltshire J, Piper C, Horn WS, Gilbert KL, et al. Trust, medication adher-

ence, and hypertension control in Southern African American men. Am J Public Health. 2012; 102

(12):2242–5. https://doi.org/10.2105/AJPH.2012.300777 PMID: 22698017

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 15 / 23

68. Fransen G a J, Mesters I, Janssen MJR, Knottnerus JA, Muris JWM. Which patient-related factors

determine self-perceived patient adherence to prescribed dyspepsia medication? Health Educ Res.

2009; 24(5):788–98. https://doi.org/10.1093/her/cyp014 PMID: 19304927

69. Fuertes JN, Boylan LS, Fontanella J a. Behavioral indices in medical care outcome: The working alli-

ance, adherence, and related factors. J Gen Intern Med. 2009; 24:80–5. https://doi.org/10.1007/

s11606-008-0841-4 PMID: 18972089

70. Gatti ME, Jacgbson KL, Gazmararian J a., Schmotzer B, Kripalani S. Relationships between beliefs

about medications and adherence. Am J Heal Pharm. 2009; 66:657–64.

71. Godin G, Cote J, Naccache H, Lambert LD, Trottier S. Prediction of adherence to antiretroviral ther-

apy: a one-year longitudinal study. AIDS Care. 2005; 17(May):493–504.

72. Halkitis PN, Kutnick AH, Slater S. The social realities of adherence to protease inhibitor regimens: sub-

stance use, health care and psychological states. J Health Psychol. 2005; 10:545–58. https://doi.org/

10.1177/1359105305053422 PMID: 16014391

73. Johnson MO, Neilands TB, Dilworth SE, Morin SF, Remien RH, Chesney MA. The role of self-efficacy

in HIV treatment adherence: Validation of the HIV Treatment Adherence Self-Efficacy Scale (HIV-

ASES). J Behav Med. 2007; 30:359–70. https://doi.org/10.1007/s10865-007-9118-3 PMID: 17588200

74. Johnson MO, Catz SL, Remien RH, Rotheram-Borus MJ, Morin SF, Charlebois E, et al. Theory-

guided, empirically supported avenues for intervention on HIV medication nonadherence: findings

from the Healthy Living Project. AIDS Patient Care STDS. 2003; 17(12):645–56. https://doi.org/10.

1089/108729103771928708 PMID: 14746658

75. Kalichman SC, Rompa D, DiFonzo K, Simpson D, Austin J, Luke W, et al. HIV treatment adherence in

women living with HIV/AIDS: research based on the Information-Motivation-Behavioral Skills model of

health behavior. J Assoc Nurses AIDS Care. 2001; 12(4):58–67. https://doi.org/10.1016/S1055-3290

(06)60217-3 PMID: 11486721

76. Kalichman SC, Kalichman MO, Cherry C, Swetzes C, Amaral CM, White D, et al. Brief behavioral self-

regulation counseling for HIV treatment adherence delivered by cell phone: an initial test of concept trial.

AIDS Patient Care STDS. 2011; 25(5):303–10. https://doi.org/10.1089/apc.2010.0367 PMID: 21457056

77. Kerr T, Marshall A, Walsh J, Palepu A, Tyndall M, Montaner J, et al. Determinants of HAART discontin-

uation among injection drug users. AIDS Care. 2005; 17(July):539–49.

78. Lewis LM, Schoenthaler AM, Ogedegbe G. Patient Factors, But Not Provider and Health Care System

Factors, Predict Medication Adherence in Hypertensive Black Men. J Clin Hypertens. 2012; 14

(4):250–5.

79. Mishali M, Omer H, Heymann a. D. The importance of measuring self-efficacy in patients with diabe-

tes. Fam Pract. 2011; 28(November 2010):82–7. https://doi.org/10.1093/fampra/cmq086 PMID:

21047940

80. Mo PKH, Mak WWS. Intentionality of medication non-adherence among individuals living with HIV/

AIDS in Hong Kong. AIDS Care. 2009; 21(6):785–95. https://doi.org/10.1080/09540120802511968

PMID: 19806492

81. Molassiotis A, Nahas-Lopez V, Chung WY, Lam SW, Li CK, Lau TF. Factors associated with adher-

ence to antiretroviral medication in HIV-infected patients. Int J STD AIDS. 2002; 13(5):301–10. https://

doi.org/10.1258/0956462021925117 PMID: 11972933

82. Murphy DA, Greenwell L, Hoffman D. Factors associated with antiretroviral adherence among HIV-

infected women with children. Women Health. 2002; 36(1):97–111. https://doi.org/10.1300/

J013v36n01_07 PMID: 12215006

83. Naar-King S, Wright K, Parsons JT, Frey M, Templin T, Lam P, et al. Healthy choices: motivational

enhancement therapy for health risk behaviors in HIV-positive youth. AIDS Educ Prev. 2006; 18(1):1–

11. https://doi.org/10.1521/aeap.2006.18.1.1 PMID: 16539572

84. Nokes K, Johnson MO, Webel A, Rose CD, Phillips JC, Sullivan K, et al. Focus on Increasing Treat-

ment Self-Efficacy to Improve Human Immunodeficiency Virus Treatment Adherence. J Nurs Scho-

larsh. 2012; 44:403–10. https://doi.org/10.1111/j.1547-5069.2012.01476.x PMID: 23121723

85. Parsons JT, Rosof E, Mustanski B. Medication adherence mediates the relationship between adher-

ence self-efficacy and biological assessments of HIV health among those with alcohol use disorders.

AIDS Behav. 2008; 12:95–103. https://doi.org/10.1007/s10461-007-9241-8 PMID: 17503172

86. Pinheiro CAT, de-Carvalho-Leite JC, Drachler ML, Silveira VL. Factors associated with adherence to

antiretroviral therapy in HIV/AIDS patients: a cross-sectional study in Southern Brazil. Brazilian J Med

Biol Res. 2002; 35(10):1173–81.

87. Remien RH, Bastos FI, Jnr VT, Raxach JC, Pinto RM, Parker RG, et al. Adherence to antiretroviral

therapy in a context of universal access in Rio de Janeiro, Brazil. AIDS Care. 2007; 19(6):740–8.

https://doi.org/10.1080/09540120600842516 PMID: 17573593

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 16 / 23

88. Resnick B, Wehren L, Orwig D. Reliability and validity of the self-efficacy and outcome expectations

for osteoporosis medication adherence scales. Orthop Nurs. 2003; 22(2):139–47. PMID: 12703398

89. Safren SA, W. Otto M, Worth JL, Salomon E, Johnson W, Mayer K, et al. Two strategies to increase

adherence to HIV antiretroviral medication: Life-Steps and medication monitoring. Behav Res Ther.

2001; 39(10):1151–62. PMID: 11579986

90. Schousboe JT, Dowd BE, Davison ML, Kane RL. Association of medication attitudes with non-persis-

tence and non-compliance with medication to prevent fractures. Osteoporos Int. 2010; 21:1899–909.

https://doi.org/10.1007/s00198-009-1141-5 PMID: 19967337

91. Shon KH, Park SS. Medication and symptom management education program for the rehabilitation of

psychiatric patients in Korea: the effects of promoting schedule on self-efficacy theory. Yonsei Med J.

2002; 43(5):579–89. https://doi.org/10.3349/ymj.2002.43.5.579 PMID: 12402370

92. Simoni JM, Frick PA, Huang B. A longitudinal evaluation of a social support model of medication

adherence among HIV-positive men and women on antiretroviral therapy. Health Psychol. 2006; 25

(1):74–81. https://doi.org/10.1037/0278-6133.25.1.74 PMID: 16448300

93. Unni E, Farris KB. Determinants of different types of medication non-adherence in cholesterol lowering

and asthma maintenance medications: A theoretical approach. Patient Educ Couns. 2011; 83(3):382–

90. https://doi.org/10.1016/j.pec.2011.02.017 PMID: 21454030

94. Wilson KJ, Doxanakis A, Fairley CK. Predictors for non-adherence to antiretroviral therapy. Sex

Health. 2005; 1(4):251–7.

95. Wolf MS, Davis TC, Osborn CY, Skripkauskas S, Bennett CL, Makoul G. Literacy, self-efficacy, and

HIV medication adherence. Patient Educ Couns. 2007; 65:253–60. https://doi.org/10.1016/j.pec.2006.

08.006 PMID: 17118617

96. Archiopoli A, Ginossar T, Wilcox B, Avila M, Hill R, Oetzel J. Factors of interpersonal communication

and behavioral health on medication self-efficacy and medication adherence. AIDS Care. 2016; 28

(12):1607–14. https://doi.org/10.1080/09540121.2016.1192577 PMID: 27320778

97. Chang Y-P, Compton P, Almeter P, Fox CH. The effect of motivational interviewing on prescription opi-

oid adherence among older adults with chronic pain. Perspect Psychiatr Care. 2015; 51(3):211–9.

https://doi.org/10.1111/ppc.12082 PMID: 25159493

98. Dewing S, Mathews C, Lurie M, Kagee A, Padayachee T, Lombard C. Predictors of poor adherence

among people on antiretroviral treatment in Cape Town, South Africa: a case-control study. AIDS

Care. 2015; 27(3):342–9. https://doi.org/10.1080/09540121.2014.994471 PMID: 25559444

99. MacDonell KK, Jacques-Tiura AJ, Naar S, Fernandez MI, Team ATN 086/106 P. Predictors of self-

reported adherence to antiretroviral medication in a multisite study of ethnic and racial minority HIV-

positive youth. J Pediatr Psychol. 2015; 41(4):419–28. https://doi.org/10.1093/jpepsy/jsv097 PMID:

26498724

100. Nafradi L, Galimberti E, Nakamoto K, Schulz PJ. Intentional and unintentional medication non-adher-

ence in hypertension: the role of health literacy, empowerment and medication beliefs. J Public Health

Res. 2016; 5(3): 762. https://doi.org/10.4081/jphr.2016.762 PMID: 28083523

101. Bolman C, Arwert TG, Vollink T. Adherence to prophylactic asthma medication: Habit strength and

cognitions. Hear Lung J Acute Crit Care. 2011; 40:63–75.

102. Carpenter DM, DeVellis RF, Fisher EB, DeVellis BM, Hogan SL, Jordan JM. The effect of conflicting

medication information and physician support on medication adherence for chronically ill patients.

Patient Educ Couns. 2010; 81(2):169–76. https://doi.org/10.1016/j.pec.2009.11.006 PMID: 20044230

103. Cha E, Erlen JA, Kim KH, Sereika SM, Caruthers D. Mediating roles of medication-taking self-efficacy

and depressive symptoms on self-reported medication adherence in persons with HIV: A question-

naire survey. Int J Nurs Stud. 2008; 45:1175–84. https://doi.org/10.1016/j.ijnurstu.2007.08.003 PMID:

17949723

104. DiIorio C, McCarty F, DePadilla L, Resnicow K, Holstad MM, Yeager K, et al. Adherence to antiretrovi-

ral medication regimens: a test of a psychosocial model. AIDS Behav. 2009; 13(1):10–22. https://doi.

org/10.1007/s10461-007-9318-4 PMID: 17978868

105. Gifford AL, Bormann JE, Shively MJ, Wright BC, Richman DD, Bozzette SA. Predictors of self-

reported adherence and plasma HIV concentrations in patients on multidrug antiretroviral regimens.

JAIDS J Acquir Immune Defic Syndr. 2000; 23(5):386–95. PMID: 10866231

106. Marc LG, Testa MA, Walker AM, Robbins GK, Shafer RW, Anderson NB, et al. Educational attainment

and response to HAART during initial therapy for HIV-1 infection. J Psychosom Res. 2007; 63:207–16.

https://doi.org/10.1016/j.jpsychores.2007.04.009 PMID: 17662759

107. Pepper JK, Carpenter DM, De Vellis RF. Does adherence-related support from physicians and part-

ners predict medication adherence for vasculitis patients? J Behav Med. 2012; 35:115–23. https://doi.

org/10.1007/s10865-012-9405-5 PMID: 22350097

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 17 / 23

108. Schoenthaler A, Ogedegbe G, Allegrante JP. Self-efficacy mediates the relationship between depres-

sive symptoms and medication adherence among hypertensive African Americans. Health Educ

Behav. 2009; 36:127–37. https://doi.org/10.1177/1090198107309459 PMID: 18077654

109. Sevelius JM, Carrico A, Johnson MO. Antiretroviral Therapy Adherence Among Transgender Women

Living With HIV. J Assoc Nurses AIDS Care. 2010; 21(3):256–64. https://doi.org/10.1016/j.jana.2010.

01.005 PMID: 20347342

110. Simoni JM, Frick P a, Lockhart D, Liebovitz D. Mediators of social support and antiretroviral adherence

among an indigent population in New York City. AIDS Patient Care STDS. 2002; 16(9):431–9. https://

doi.org/10.1089/108729102760330272 PMID: 12396695

111. Bogart LM, Gray-Bernhardt ML, Catz SL, Hartmann BR, Otto-Salaj LL. Social and temporal compari-

sons made by individuals living with HIV disease: Relationships to adherence behavior. J Appl Soc

Psychol. 2002; 32:1551–76.

112. Edworthy SM, Domazei N, Talavera R, Devins GM. Illness intrusiveness: An intervening factor

between symptoms and quality of life in patients with systemic lupus erythematosus. Arthritis and

Rheumatism. 1998. S221–S221.

113. Johnson MO, Chesney M a, Goldstein RB, Remien RH, Catz S, Gore-Felton C, et al. Positive provider

interactions, adherence self-efficacy, and adherence to antiretroviral medications among HIV-infected

adults: A mediation model. AIDS Patient Care STDS. 2006; 20(4):258–68. https://doi.org/10.1089/

apc.2006.20.258 PMID: 16623624

114. Bennett P, Rowe A, Katz D. Reported adherence with preventive asthma medication: a test of protec-

tion motivation theory. Psychol Health Med. 1998; 3(4):347–54.

115. Bosma OH, Vermeulen KM, Verschuuren E a., Erasmus ME, Van Der Bij W. Adherence to immuno-

suppression in adult lung transplant recipients: Prevalence and risk factors. J Hear Lung Transplant.

2011; 30(11):1275–80.

116. Russell CL, Cetingok M, Hamburger KQ, Owens S, Thompson D, Hathaway D, et al. Medication

adherence in older renal transplant recipients. Clin Nurs Res. 2010; 19:95–112. https://doi.org/10.

1177/1054773810362039 PMID: 20185804

117. Samal L, Saha S, Chander G, Korthuis PT, Sharma RK, Sharp V, et al. Internet health information

seeking behavior and antiretroviral adherence in persons living with HIV/AIDS. AIDS Patient Care

STDS. 2011; 25(7):445–9. https://doi.org/10.1089/apc.2011.0027 PMID: 21682586

118. Clark NM, Dodge J a. Exploring self-efficacy as a predictor of disease management. Health Educ

Behav. 1999; 26:72–89. https://doi.org/10.1177/109019819902600107 PMID: 9952053

119. Warren-Findlow J, Seymour RB, Shenk D. Intergenerational transmission of chronic illness self-care:

Results from the caring for hypertension in African American families study. Gerontologist. 2011; 51

(1):64–75. https://doi.org/10.1093/geront/gnq077 PMID: 20864590

120. Anderson KO, Dowds BN, Pelletz RE, Edwards WT, Peeters-Asdourian C. Development and initial

validation of a scale to measure self-efficacy beliefs in patients with chronic pain. Pain. 1995; 63

(1):77–83. PMID: 8577493

121. Kobau R, DiIorio C. Epilepsy self-management: a comparison of self-efficacy and outcome expec-

tancy for medication adherence and lifestyle behaviors among people with epilepsy. Epilepsy Behav.

2003; 4(3):217–25. PMID: 12791322

122. Gastal DA, Pinheiro RT, Vazquez DP. Self-efficacy scale for Brazilians with type 1 diabetes. Sao

Paulo Med J. 2007; 125(2):96–101. PMID: 17625707

123. Chen HF, Tsai YF, Lin YP, Shih MS, Chen JC. The relationships among medicine symptom distress,

self-efficacy, patient-provider relationship, and medication compliance in patients with epilepsy. Epi-

lepsy Behav. 2010; 19(1):43–9. https://doi.org/10.1016/j.yebeh.2010.06.007 PMID: 20719572

124. Chen S-Y, Sheu S, Chang C-S, Wang T-H, Huang M-S. The effects of the self-efficacy method on

adult asthmatic patient self-care behavior. J Nurs Res. 2010; 18(4):266–74. https://doi.org/10.1097/

NRJ.0b013e3181fbe33f PMID: 21139446

125. Fraser C, Hadjimichael O, Vollmer T. Predictors of Adherence to Copaxone Therapy in Individuals

with Relapsing-Remitting Multiple Sclerosis. J Neurosci Nurs. 2001; 33(5):231–9. PMID: 11668881

126. Fraser C, Hadjimichael O, Vollmer T. Predictors of Adherence to Glatiramer Acetate Therapy in Indi-

viduals with Self-Reported Progressive Forms of Multiple Sclerosis. J Neurosci Nurs. 2003; 35

(3):163–70. PMID: 12830664

127. Fraser C, Morgante L, Hadjimichael O, Vollmer T. A Prospective Study of Adherence to Glatiramer Ace-

tate in Individuals with Multiple Sclerosis. J Neurosci Nurs. 2004; 36(3):120&hyhen. PMID: 15233411

128. Heckman BD, Ellis G. Preventive medication adherence in African American and Caucasian head-

ache patients. Headache. 2011; 51:520–32. https://doi.org/10.1111/j.1526-4610.2011.01866.x PMID:

21457237

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 18 / 23

129. Khdour MR, Hawwa AF, Kidney JC, Smyth BM, McElnay JC. Potential risk factors for medication non-

adherence in patients with chronic obstructive pulmonary disease (COPD). Eur J Clin Pharmacol.

2012; 68:1365–73. https://doi.org/10.1007/s00228-012-1279-5 PMID: 22476392

130. Kim JH, Kim GS, Kim EJ, Park S, Chung N, Chu SH. Factors affecting medication adherence and

anticoagulation control in Korean patients taking warfarin. J Cardiovasc Nurs. 2011; 26(6):466–74.

https://doi.org/10.1097/JCN.0b013e31820914e7 PMID: 21912274

131. Li X, Huang L, Wang H, Fennie KP, He G, Williams AB. Stigma Mediates the Relationship Between

Self-Efficacy, Medication Adherence, and Quality of Life Among People Living with HIV/AIDS in

China. AIDS Patient Care STDS. 2011; 25(11):665–71. https://doi.org/10.1089/apc.2011.0174 PMID:

22023316

132. Mohr DC, Boudewyn a C, Likosky W, Levine E, Goodkin DE. Injectable medication for the treatment of

multiple sclerosis: the influence of self-efficacy expectations and injection anxiety on adherence and

ability to self-inject. Ann Behav Med. 2001; 23:125–32. PMID: 11394554

133. Molloy GJ, Randall G, Wikman A, Perkins-Porras L, Messerli-Burgy N, Steptoe A. Type D personality,

self-efficacy, and medication adherence following an acute coronary syndrome. Psychosom Med.

2012; 74(1):100–6. https://doi.org/10.1097/PSY.0b013e31823a5b2f PMID: 22155940

134. Morasco BJ, Turk DC, Donovan DM, Dobscha SK. Risk for prescription opioid misuse among patients

with a history of substance use disorder. Drug Alcohol Depend. 2013; 127(1–3):193–9. https://doi.org/

10.1016/j.drugalcdep.2012.06.032 PMID: 22818513

135. Scherer YK, Bruce S. Knowledge, attitudes, and self-efficacy and compliance with medical regimen,

number of emergency department visits, and hospitalizations in adults with asthma. Hear Lung J

Acute Crit Care. 2001; 30(August):250–7.

136. Warren-Findlow J, Seymour RB, Huber LRB. The association between self-efficacy and hypertension

self-care activities among African American adults. J Community Health. 2012; 37:15–24. https://doi.

org/10.1007/s10900-011-9410-6 PMID: 21547409

137. Sarkar U, Fisher L, Schillinger D. Is self-efficacy associated with diabetes self-management across

race/ethnicity and health literacy? Diabetes Care. 2006 Apr; 29(4):823–9. PMID: 16567822

138. Yu ZL, Yeoh LY, Seow YY, Luo XC, Griva K. Evaluation of adherence and depression among patients

on peritoneal dialysis. Singapore Med J. 2012; 53(May 2010):474–80. PMID: 22815017

139. Zwibel H, Pardo G, Smith S, Denney D, Oleen-Burkey M. A multicenter study of the predictors of

adherence to self-injected glatiramer acetate for treatment of relapsing-remitting multiple sclerosis. J

Neurol. 2011; 258:402–11. https://doi.org/10.1007/s00415-010-5766-2 PMID: 20922405

140. Corless IB, Wantland D, Kirksey KM, Nicholas PK, Human S, Arudo J, et al. Exploring the Contribution

of General Self-Efficacy to the Use of Self-Care Symptom Management Strategies by People Living

with HIV Infection. AIDS Patient Care STDS. 2012; 26(6):335–43. https://doi.org/10.1089/apc.2011.

0404 PMID: 22612448

141. Luszczynska A, Sarkar Y, Knoll N. Received social support, self-efficacy, and finding benefits in dis-

ease as predictors of physical functioning and adherence to antiretroviral therapy. Patient Educ

Couns. 2007; 66(1):37–42. https://doi.org/10.1016/j.pec.2006.10.002 PMID: 17097259

142. Ponieman D, Wisnivesky JP, Leventhal H, Musumeci-Szabo TJ, Halm EA. Impact of positive and neg-

ative beliefs about inhaled corticosteroids on adherence in inner-city asthmatic patients. Ann Allergy,

Asthma Immunol. 2009; 103(1):38–42.

143. Mann DM, Ponieman D, Leventhal H, Halm EA. Predictors of adherence to diabetes medications: the

role of disease and medication beliefs. J Behav Med. 2009; 32(3):278–84. https://doi.org/10.1007/

s10865-009-9202-y PMID: 19184390

144. de Guzman AB, Guevara KIJ, Guiang FJB, Gutierrez ALI, Habaluyas AS, Hizon MAP, et al. Develop-

ing a Model of Medication Adherence among Filipino Elderly. Educ Gerontol. 2013; 39(5):298–313.

145. Valeberg BT, Miaskowski C, Hanestad BR, Bjordal K, Moum T, Rustøen T. Prevalence rates for and

predictors of self-reported adherence of oncology outpatients with analgesic medications. Clin J Pain.

2008; 24(7):627–36. https://doi.org/10.1097/AJP.0b013e31816fe020 PMID: 18716502

146. Mann DM, Ponieman D, Leventhal H, Halm EA. Predictors of adherence to diabetes medications: The

role of disease and medication beliefs. J Behav Med. 2009; 32:278–84. https://doi.org/10.1007/

s10865-009-9202-y PMID: 19184390

147. Liu Y, Malin JL, Diamant AL, Thind A, Maly RC. Adherence to adjuvant hormone therapy in low-income

women with breast cancer: The role of provider-patient communication. Breast Cancer Res Treat.

2013; 137:829–36. https://doi.org/10.1007/s10549-012-2387-8 PMID: 23263740

148. Curtin RB, Walters BAJ, Schatell D, Pennell P, Wise M, Klicko K. Self-efficacy and self-management

behaviors in patients with chronic kidney disease. Adv Chronic Kidney Dis. 2008; 15(2):191–205.

https://doi.org/10.1053/j.ackd.2008.01.006 PMID: 18334246

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 19 / 23

149. Kamau TM, Olson VG, Zipp GP, Clark M. Coping Self-Efficacy as a Predictor of Adherence to Antire-

troviral Therapy in Men and Women Living with HIV in Kenya. AIDS Patient Care STDS. 2011; 25

(9):557–61. https://doi.org/10.1089/apc.2011.0125 PMID: 21777140

150. Robbins RN, D’Aquila E, Morgello S, Byrd D, Remien RH, Mindt MR. Cultural Influences on Antiretrovi-

ral Therapy Adherence Among HIV-Infected Puerto Ricans. J Assoc Nurses AIDS Care. 2012; 23

(6):531–8. https://doi.org/10.1016/j.jana.2011.12.006 PMID: 22525858

151. Shively M, Smith T, Bormann J, Gifford A. Evaluating self-efficacy for HIV disease management skills.

AIDS Behav. 2002; 6(4).

152. Wallston BS, Wallston KA, Kaplan GD, Maides SA. Development and validation of the health locus of

control (HLC) scale. J Consult Clin Psychol. 1976; 44(4):580. PMID: 939841

153. Wallston K a, Stein MJ, Smith C a. Form C of the MHLC scales: a condition-specific measure of locus

of control. J Pers Assess. 1994; 63(3):534–53. https://doi.org/10.1207/s15327752jpa6303_10 PMID:

7844739

154. Davis DP, Jandrisevits MD, Iles S, Weber TR, Gallo LC. Demographic, Socioeconomic, and Psycho-

logical Factors Related to Medication Non-adherence among Emergency Department Patients. J

Emerg Med. 2009; 43(5):773–85. https://doi.org/10.1016/j.jemermed.2009.04.008 PMID: 19464136

155. Halimi L, Vachier I, Varrin M, Godard P, Pithon G, Chanez P. Interference of psychological factors in

difficult-to-control asthma. Respir Med. 2007; 101:154–61. https://doi.org/10.1016/j.rmed.2006.03.

036 PMID: 16857356

156. Halimi L, Pry R, Pithon G, Godard P, Varrin M, Chanez P. Severe asthma and adherence to peak flow

monitoring: longitudinal assessment of psychological aspects. J Psychosom Res. 2010; 69(4):331–

40. https://doi.org/10.1016/j.jpsychores.2010.02.007 PMID: 20846534

157. Fransen G a J, Mesters I, Janssen MJR, Knottnerus J a., Muris JWM. Which patient-related factors

determine self-perceived patient adherence to prescribed dyspepsia medication? Health Educ Res.

2009; 24:788–98. https://doi.org/10.1093/her/cyp014 PMID: 19304927

158. Kaya Z, Erkan F, Ozkan M, Ozkan S, Kocaman N, Ertekin BA, et al. Self-management plans for

asthma control and predictors of patient compliance. J Asthma. 2009; 46:270–5. https://doi.org/10.

1080/02770900802647565 PMID: 19373635

159. Wang PS, Bohn RL, Knight E, Glynn RJ, Mogun H, Avorn J. Noncompliance with antihypertensive

medications: The impact of depressive symptoms and psychosocial factors. J Gen Intern Med. 2002;

17:504–11. https://doi.org/10.1046/j.1525-1497.2002.00406.x PMID: 12133140

160. Cotton S, Antill JK. Noncompliance: medical and psychological aspects. Aust Psychol. 1984; 19

(2):193–204.

161. Holloway RL, Rogers JC, Gershenhorn SL. Differences between patient and physician perceptions of

predicted compliance. Fam Pract. 1992; 9(3):318–22. PMID: 1459389

162. Katerndahl DA. Locus of control and field dependence in prediction. J Nerv Ment Dis. 2001; 189

(5):335–8. PMID: 11379981

163. Barclay TR, Hinkin CH, Castellon SA, Mason KI, Reinhard MJ, Marion SD, et al. Age-associated pre-

dictors of medication adherence in HIV-positive adults: health beliefs, self-efficacy, and neurocognitive

status. Health Psychol. 2007; 26(1):40–9. https://doi.org/10.1037/0278-6133.26.1.40 PMID:

17209696

164. Bazargan M, Barbre AR, Hamm V. Failure to have prescriptions filled among Black elderly. J Aging

Health. 1993; 5(2):264–82. https://doi.org/10.1177/089826439300500207 PMID: 10125448

165. Darling CA, Olmstead SB, Lund VE, Fairclough JF. Bipolar Disorder: Medication Adherence and Life

Contentment. Arch Psychiatr Nurs. 2008; 22(3):113–26. https://doi.org/10.1016/j.apnu.2008.02.004

PMID: 18505693

166. Hong TB, Oddone EZ, Dudley TK, Bosworth HB. Medication barriers and anti-hypertensive medication

adherence: the moderating role of locus of control. Psychol Health Med. 2006; 11(1):20–8. https://doi.

org/10.1080/14786430500228580 PMID: 17129892

167. O’Hea EL, Grothe KB, Bodenlos JS, Boudreaux ED, White M a, Brantley PJ. Predicting medical regi-

men adherence: the interactions of health locus of control beliefs. J Health Psychol. 2005; 10:705–17.

https://doi.org/10.1177/1359105305055330 PMID: 16033792

168. Stanton AL. Determinants of adherence to medical regimens by hypertensive patients. J Behav Med.

1987; 10(4):377–94. PMID: 3669072

169. Theofilou P. Medication adherence in Greek hemodialysis patients: The contribution of depression

and health cognitions. Int J Behav Med. 2013; 20:311–8. https://doi.org/10.1007/s12529-012-9231-8

PMID: 22407452

170. Wulandari LPL, Craig P, Whelan AK. Foetal Health Locus of Control and iron supplementation adher-

ence among pregnant women in Bali. J Reprod Infant Psychol. 2013; 31(1):94–101.

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 20 / 23

171. Raiz LR, Kilty KM, Henry ML, Ferguson RM. Medication compliance following renal transplantation.

Transplantation. 1999; 68(1):51–5. PMID: 10428266

172. Ahmedani BK, Peterson EL, Wells KE, Rand CS, Williams LK. Asthma medication adherence: the role

of God and other health locus of control factors. Ann Allergy. 2013; 110(2):75–79. e2.

173. Altice FL, Mostashari F, Friedland GH. Trust and the acceptance of and adherence to antiretroviral

therapy. J Acquir Immune Defic Syndr. 2001; 28(1):47–58. PMID: 11579277

174. Apter AJ, Reisine ST, Affleck G, Barrows E, ZuWallack RL. Adherence with twice-daily dosing of

inhaled steroids: Socioeconomic and health-belief differences. Am J Respir Crit Care Med. 1998;

157:1810–7. https://doi.org/10.1164/ajrccm.157.6.9712007 PMID: 9620910

175. Bane C, Hughes CM, McElnay JC. The impact of depressive symptoms and psychosocial factors on

medication adherence in cardiovascular disease. Patient Educ Couns. 2006; 60:187–93. https://doi.

org/10.1016/j.pec.2005.01.003 PMID: 16253468

176. Budd RJ, Hughes ICT, Smith JA. Health beliefs and compliance with antipsychotic medication. Br J

Clin Psychol. 1996; 35(3):393–7.

177. Graveley EA, Oseasohn CS. Multiple drug regimens: medication compliance among veterans 65

years and older. Res Nurs Health. 1991; 14(1):51–8. PMID: 2017581

178. Hargrave R, Remler MP. Noncompliance. J Natl Med Assoc. 1996; 88(1):7, 11. PMID: 8583495

179. Lamba S, Nagurka R, Desai KK, Chun SJ, Holland B, Koneru B. Self-reported non-adherence to

immune-suppressant therapy in liver transplant recipients: Demographic, interpersonal, and intraper-

sonal factors. Clin Transplant. 2012; 26(2):328–35. https://doi.org/10.1111/j.1399-0012.2011.01489.x

PMID: 21955028

180. Lynam I, Catley D, Goggin K, Rabinowitz JL, Gerkovich MM, Williams K, et al. Autonomous regulation

and locus of control as predictors of antiretroviral medication adherence. J Health Psychol. 2009;

14:578–86. https://doi.org/10.1177/1359105309103577 PMID: 19383658

181. McDonald-Miszczak L, Maki SA, Gould ON. Self-reported medication adherence and health status in

late adulthood: The role of beliefs. Exp Aging Res. 2000; 26(3):189–207. https://doi.org/10.1080/

036107300404859 PMID: 10919066

182. McDonough EM, Boyd JH, Varvares MA, Maves MD. Relationship between psychological status and

compliance in a sample of patients treated for cancer of the head and neck. Head Neck. 1996; 18

(3):269–76. https://doi.org/10.1002/(SICI)1097-0347(199605/06)18:3<269::AID-HED9>3.0.CO;2-Y

PMID: 8860769

183. Reach G, Michault a., Bihan H, Paulino C, Cohen R, Le Clesiau H. Patients’ impatience is an indepen-

dent determinant of poor diabetes control. Diabetes Metab. 2011; 37(6):497–504. https://doi.org/10.

1016/j.diabet.2011.03.004 PMID: 21550831

184. Weng FL, Israni AK, Joffe MM, Hoy T, Gaughan CA, Newman M, et al. Race and electronically mea-

sured adherence to immunosuppressive medications after deceased donor renal transplantation. J

Am Soc Nephrol. 2005; 16(6):1839–48. https://doi.org/10.1681/ASN.2004121059 PMID: 15800121

185. Williams GC, Rodin GC, Ryan RM, Grolnick WS, Deci EL. Autonomous regulation and long-term med-

ication adherence in adult outpatients. Health Psychol. 1998; 17(3):269–76. PMID: 9619477

186. Craig H, Wright B. Nonadherence to prophylactic medication: Negative attitudes toward doctors a

strong predictor. Aust Fam Physician. 2012; 41(10):815. PMID: 23210108

187. Kamolz T. Analysis of medical compliance in gastro-oesophageal reflux disease patients referred to

pre-surgical examination. Dig Liver Dis. 2002; 34:183–9. PMID: 11990390

188. Frazier PA, Davis-Ali SH, Dahl KE. Correlates of noncompliance among renal transplant recipients.

Clin Transplant. 1994; 8(6):550–7. PMID: 7865918

189. Abbott J, Dodd M, Webb a K. Health perceptions and treatment adherence in adults with cystic fibro-

sis. Thorax. 1996; 51:1233–8. PMID: 8994521

190. Weng FL, Israni AK, Joffe MM, Hoy T, Gaughan C a, Newman M, et al. Race and electronically mea-

sured adherence to immunosuppressive medications after deceased donor renal transplantation. J

Am Soc Nephrol. 2005; 16(19):1839–48.

191. Aversa SL, Kimberlin C. Psychosocial aspects of antiretroviral medication use among HIV patients.

Patient Educ Couns. Elsevier; 1996; 29(2):207–19. PMID: 9006237

192. Sajatovic M, Ignacio R V., West J a., Cassidy K a., Safavi R, Kilbourne AM, et al. Predictors of nonad-

herence among individuals with bipolar disorder receiving treatment in a community mental health

clinic. Compr Psychiatry. 2009; 50(2):100–7. https://doi.org/10.1016/j.comppsych.2008.06.008 PMID:

19216885

193. Schneider B. Multidimensional health locus of control as partial predictor of serum phosphorus in

chronic hemodialysis. Psychol Rep. 1992; 70(3 Pt 2):1171–4.

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 21 / 23

194. Myers LB, Myers F. The relationship between control beliefs and self-reported adherence in adults

with cystic fibrosis. Psychol Health Med. 1999; 4(4):387–91.

195. Sajatovic M, Micula-Gondek W, Tatsuoka C, Bialko C. The relationship of gender and gender identity

to treatment adherence among individuals with bipolar disorder. Gend Med. 2011; 8(4):261–8. https://

doi.org/10.1016/j.genm.2011.06.002 PMID: 21763217

196. Williams GC, Rodin GC, Ryan RM, Grolnick WS, Deci EL. Autonomous regulation and long-term med-

ication adherence in adult outpatients. Heal Psychol. 1998; 17(3):269.

197. Lamba S, Nagurka R, Desai KK, Chun SJ, Holland B, Koneru B. Self-reported non-adherence to

immune-suppressant therapy in liver transplant recipients: demographic, interpersonal, and intraper-

sonal factors. Clin Transplant. 2012; 26(2):328–35. https://doi.org/10.1111/j.1399-0012.2011.01489.x

PMID: 21955028

198. Berglund E, Lytsy P, Westerling R. Adherence to and beliefs in lipid-lowering medical treatments: A

structural equation modeling approach including the necessity-concern framework. Patient Educ

Couns. 2013; 91(1):105–12. https://doi.org/10.1016/j.pec.2012.11.001 PMID: 23218590

199. Voils CI, Steffens DC, Flint EP, Bosworth HB. Social support and locus of control as predictors of

adherence to antidepressant medication in an elderly population. Am J Geriatr Psychiatry. 2005;

13:157–65. https://doi.org/10.1176/appi.ajgp.13.2.157 PMID: 15703325

200. O’Hea EL, Moon S, Grothe KB, Boudreaux E, Bodenlos JS, Wallston K, et al. The interaction of locus

of control, self-efficacy, and outcome expectancy in relation to HbA1c in medically underserved indi-

viduals with type 2 diabetes. J Behav Med. 2009; 32:106–17. https://doi.org/10.1007/s10865-008-

9188-x PMID: 19089606

201. Christensen AJ, Wiebe JS, Benotsch EG, Lawton WJ. Perceived health competence, health locus of

control, and patient adherence in renal dialysis. Cognit Ther Res. 1996; 20(4):411–21.

202. Christensen AJ, Wiebe JS, Lawton WJ. Cynical hostility, powerful others control expectancies, and

patient adherence in hemodialysis. Psychosom Med. 1997; 59(1):307–12.

203. Atkins L, Fallowfield L. Intentional and non-intentional non-adherence to medication amongst breast

cancer patients. Eur J Cancer. 2006; 42(14):2271–6. https://doi.org/10.1016/j.ejca.2006.03.004

PMID: 16644208

204. Schneider A, Wensing M, Quinzler R, Bieber C, Szecsenyi J. Higher preference for participation in

treatment decisions is associated with lower medication adherence in asthma patients. Patient Educ

Couns. 2007; 67:57–62. https://doi.org/10.1016/j.pec.2007.01.019 PMID: 17346917

205. Gremigni P, Bacchi F, Turrini C, Cappelli G, Albertazzi A, Bitti PER. Psychological factors associated

with medication adherence following renal transplantation. Clin Transplant. 2007; 21(4):710–5.

206. Cholowski K, Cantwell R. Predictors of medication compliance among older heart failure patients. Int J

Older People Nurs. 2007; 2(4):250–62. https://doi.org/10.1111/j.1748-3743.2007.00082.x PMID:

20925839

207. Kennedy S, Goggin K, Nollen N. Adherence to HIV medications: Utility of the theory of self-determina-

tion. Cognit Ther Res. 2004; 28(5):611–28.

208. Molassiotis A, Morris K, Trueman I. The importance of the patient-clinician relationship in adherence

to antiretroviral medication. Int J Nurs Pract. 2007; 13:370–6. https://doi.org/10.1111/j.1440-172X.

2007.00652.x PMID: 18021166

209. Williams GC, Patrick H, Niemiec CP, Williams LK, Divine G, Lafata JE, et al. Reducing the health risks

of diabetes: how self-determination theory may help improve medication adherence and quality of life.

Diabetes Educ. 2009; 35:484–92. https://doi.org/10.1177/0145721709333856 PMID: 19325022

210. Peyrot M, Rubin RR. Structure and correlates of diabetes-specific locus of control. Diabetes Care.

1994; 17(9):994–1001. PMID: 7988321

211. Stenstrom CH, Arge B, Sundbom A. Home exercise and compliance in inflammatory rheumatic dis-

eases—a prospective clinical trial. J Rheumatol. 1997; 24(3):470–6. PMID: 9058651

212. Cvengros JA, Christensen AJ, Hillis SL, Rosenthal GE. Patient and physician attitudes in the health

care context: Attitudinal symmetry predicts patient satisfaction and adherence. Ann Behav Med. 2007;

33:262–8. https://doi.org/10.1080/08836610701358086 PMID: 17600453

213. Christensen AJ, Howren MB, Hillis SL, Kaboli P, Carter BL, Cvengros JA, et al. Patient and physician

beliefs about control over health: Association of symmetrical beliefs with medication regimen adher-

ence. J Gen Intern Med. 2010; 25:397–402. https://doi.org/10.1007/s11606-010-1249-5 PMID:

20174972

214. Ridic G, Gleason S, Ridic O. Comparisons of Health Care Systems in the United States, Germany and

Canada. Mater Sociomed. 2012; 24(2): 112–120. https://doi.org/10.5455/msm.2012.24.112-120

PMID: 23678317

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 22 / 23

215. Schulz PJ, Nakamoto K. Health literacy and patient empowerment in health communication: the

importance of separating conjoined twins. Patient Educ Couns. 2013; 90(1):4–11. https://doi.org/10.

1016/j.pec.2012.09.006 PMID: 23063359

216. Chiu C, Feuz M a., McMahan RD, Miao Y, Sudore RL. “doctor, make my decisions”: Decision control

preferences, advance care planning, and satisfaction with communication among diverse older adults.

J Pain Symptom Manage. 2016; 51(1):33–40. https://doi.org/10.1016/j.jpainsymman.2015.07.018

PMID: 26342727

217. Charles C, Gafni A, Whelan T. Decision-making in the physician-patient encounter: Revisiting the

shared treatment decision-making model. Soc Sci Med. 1999; 49:651–61. PMID: 10452420

218. Nafradi L, Nakamoto K, Csabai M, Papp-zipernovszky O, Schulz PJ. An empirical test of the Health

Empowerment Model : Does patient empowerment moderate the effect of health literacy on health sta-

tus ? Patient Educ Couns. 2017

219. Charles C, Gafni A, Whelan T. Shared decision-making in the medical encounter: What does it mean?

(Or it takes, at least two to tango). Soc Sci Med. 1997; 44(5):681–92. PMID: 9032835

220. Hooper L. Publication bias : what is it ? How do we measure it ? How do we avoid it ? Open Access

Journal of Clinical Trials. 2013; 5:71–81.

A systematic review of the link between empowerment and adherence

PLOS ONE | https://doi.org/10.1371/journal.pone.0186458 October 17, 2017 23 / 23